Dollond. I. John, an English optician, born in London, June 10, 1706, died there, Nov. 30, 1761. He was descended from a French refugee family, and was originally a silk weaver, but spent his evenings in studying various sciences and languages, and made a translation of the Greek Testament into Latin. His preference was for optics, and he went into partnership with his son as an optical instrument manufacturer at Spitalfields. He commenced a series of experiments on the dispersion of light and other subjects connected with the improvement of telescopes and microscopes, the results of which were communicated to the royal society in a series of papers, which appeared in its "Transactions" during 1768, 1754, and 1758. For these he received the Copley medal, and in 1761 was elected a member of the society, and appointed optician to the king. He was the discoverer of the laws of the dispersion of light, and the inventor of the achromatic telescope. II. Peter, son of the preceding, born about 1730, died in 1820. Soon after entering into partnership with his father he removed his business from Spitalfields to St. Paul's churchyard, where he met with great success.

He made several important improvements in optical instruments, and contributed some valuable papers to the "Transactions" of the royal society, one of which was a vindication of his fathers claim to the discovery of the true theory of the refrangi-bility of light, which appeared in 1781).